Why do 2 stroke engines use springs to.....

[mrbigal81]

I was just wondering why 2 stroke engines use springs to hold the exhaust to the head? why not bolt it on like the 4 stroke engines??

 

[rickyd]

Vibration perhaps?? : :think:

 

[jmics19067]

that would be my guess. Since the expansion chamber on a two stroke is held on by springs and then mounted with rubber mounts my guess is that the heavier weight of the 2 stroke pipe yet made with thinner material would crack easier. Or maybe becasue the 2 stroke pipe is so susceptible to crash damage from its size that they mount it loose so you won't bend or break the exhaust spigot off the cylinder.

now before anybody yells at me about how I say a two stoke exhaust is heavier than a four stoke I am only talking about the pipe that connects to the cylinder. A four stroke head pipe is going to be rather short compared to a two stroke expansion chamber so you are going to have less momentum of a bob weight<I think that would be the proper term>

but it is only a guess

 

[Kwackers]

Or to phrase the question another way why do 4 strokes use stupid studs that corrode and seize then snap off ?

 

[mrbigal81]

i would much rather have bolts holding on my exhaust. I have a 500 which wears out the gaskets quick and then rattles and leaks.

 

[motometal]

have you tried hi-temp silicone? I don't think I have ever had one leak once I started using silicone. The only way it will leak is if you don't clean the oil off first (use solvent, etc.) or if the pipe can move enough to break down the silicone (bad mounts?)

good luck!

 

[dale williams]

I think it has two excuses. Two stroke engines have cooler exhaust temperatures than four stroke engines and thus a couple of O-rings will work. This same system would not survive the temperature of a four-stroke engine. The O-ring system is much cheaper to design, manufacture and maintain. An as you point out is less susceptible to cracks because it won't transfer as much stress from vibration.

 

[wornknobby]

its all bout vibration

 

[Porstala F9]

It is all vibrations. My new 250 vibrates so much, I cant stand to sit on it when I warm it up anymore, I get off and stand up and rev it.

 

[Peer Lovell]

Its vibration and slight "rocking" of the engine. Its no different than the exhaust on a front wheel drive car. The manifold may be bolted, but the balance of the exhaust is mounted on rubber hangers.

 

[NO HAND]

have you tried hi-temp silicone? I don't think I have ever had one leak once I started using silicone. The only way it will leak is if you don't clean the oil off first (use solvent, etc.) or if the pipe can move enough to break down the silicone (bad mounts?)

good luck!

Motometal, I tried this trick of yours and it works awesome. I was soo tired of the spooge drooling from the front pipe junction. Now, it's all clean and I noticed it is a litle bit quieter too. :thumb:

 

[bedell99]

one reason guys. If you crash it will break your cylinder if it was bolted directly to your cylinder. the springs allow some give.

Erik

 

[Rooster]

Hmmm, strange, my old TY250 is a 2stroke and has a bolted head pipe? I have no idea why!

 

[teamextreme]

This high temp silicone of which you speak, are we talking about the car repair variety like RTV, just high temp, and smear it on the joint/o-ring? If not, what kind are you talking about. I just bought my son a used 2000 CR80 and it drools spooge out the pipe/head mating surface like a mofo. Hopefully this will help. I was also told that these bikes don't come with an o-ring. Anyone know if this is true, and if so can one be put in? Thanks from a first-time post'in newbie.

 

[sunnyboy]

SOME 4-STROKES ALSO USE SPRINGS-the springs are thier because of vibration,i have a yamaha 100 enduro no springs just bolts.the wieght is not it since the pipe has other mounts,try removeing the springs the pipe should stay in place.when you wear out your gasket the pipe rattles even more causing wear to the aluminum piece attached to your cylinder this happens fast simply replacing the gasket dosnt fix the worn part(cant think of its name)replaceing the worn part brings things back to the proper fit.this is why that part is not part of the cylinder casting so it can be replaced.using the high temp sil. to seal it up after fixing is the way to go but let it cure a couple of days before running

 

[TheJunkMan]

My Gas Gas trials bike bolts to the cylinder, and I disasembled the bike when I got it and anti sezed all the bolts so now that is is old everything comes apart.

 

[Racer#213]

i read something on this a while back. I think it's something bc the pressure a 4-stroke puts out is much greater than a 2-stroke. SO all the 2-strok needs is springs. The four-stroke needs bolts, bc the back pressure is so great that it would break the springs.

 

[NO HAND]

This high temp silicone of which you speak, are we talking about the car repair variety like RTV, just high temp, and smear it on the joint/o-ring? If not, what kind are you talking about. I just bought my son a used 2000 CR80 and it drools spooge out the pipe/head mating surface like a mofo. Hopefully this will help. I was also told that these bikes don't come with an o-ring. Anyone know if this is true, and if so can one be put in? Thanks from a first-time post'in newbie.

I have tried a few different and found RTV is good but almost too strong and gives you a hard time to remove the pipe on the next top end. Just hi-temp or even regular window silicone is strong enough to keep the joint totally leak free and wont be hard to remove. I remember my 00CR125 had a pipe gasket made out of tin. It was totally worthless and it needed silicone. The o-ring system on my 03CR250 is supposed to be better but still leaks just as bad; so silicone is still my best friend. :)